With the AR A4 OT combo, you dont really “need” anything, and there’s not a definitive proper way of doing things.
These 3 boxes together is already a lot to manage and learn.
However, depending on how you like to work, there’s lots of things you could add to the rig, and so many ways to connect it all.
At this point I like using all 3 of these boxes as one instrument kind of.
As stated above, A4 and AR go into the OT, and the OT Main is my final output, I use the Cue outs to send tracks to effects pedals and such.
In the end I have OT’s Main outs going to a small mixer, and the cue outs to fx then to the small mixer.
The OT drives everything else, Midi OUT to the AR, Thru to the A4, and they are set up so pattern changes on the OT change the patterns on the other 2 boxes.
With the Elektron boxes hooked up this way, I can add external synths or whatever and route them to the inputs of the A4 for some flexible volume control plus effects, or in to the AR with no volume control, but you do get the AR’s compressor.
I can drive external synths with midi from the OT, or even the CV outs from the A4.
I dont really use Overbridge, but when I do, I sync the A4 and AR to Ableton using OB (tight sync), and use a Mio USB to Midi adapter to slave the OT to Live. The OT drags a bit on the first few bars, and it has to be delay compensated to match the others, but it works pretty good otherwise.
http://www.iconnectivity.com/products/midi/mio
I am often back and fourth on adding a mixer and using the individual outs on the RYTM, and get more flexible routing.
I keep finding ways to put it off be cause I like the size of the rig as is.
I thought I might get the Soundcraft MTK mixer when they came out, but I’m not so sure anymore.
Holding out to see if Elektron delivers a solution with this new product they are teasing.
When adding more synths and external gear that has midi, people tend to get thru boxes and mergers.
Dont do that, just get a midi router, like a Midi Express XT, get an old one if your on a budget.
This makes cross talk between synths a breeze, especially if your driving from the OT, but you also have a midi keyboard controller.
For whatever it’s worth, I would maybe not get all 3 boxes at once.
I’d get the OT, and one of the others thats most appealing.
You may realize you dont want the other, or that you really really gotta have all of em.
Like many, you might not jive with the OT, but you might love the analog series combo.
At this point the OT is really the odd duck in the trio, but it’s SO amazing.
Take time with each one of them separately, you’ll be glad you did.